Nano-Titania/Nafion (TiO
2
/Nafion) hybrid membranes were prepared by recasting, using Nafion solution and TiO
2
anatase hydrosol as the raw materials. The microstructure of the hybrid membrane was ...characterized by X-ray diffraction, high-resolution transmission electron microscopy (HR-TEM), X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy (FT-IR). The photocatalytic properties of TiO
2
/Nafion hybrid membranes were evaluated. Furthermore, endurance of photocatalytic activity of the hybrid membrane was investigated. The results indicate that the TiO
2
Nanoparticles are bounded to Nafion molecule via Ti-O-S bonds and the formed flocculates are distributed homogeneously throughout the recasting Nafion membrane, while the initial pure anatase TiO
2
nanoparticles remain intact in re-crystallized membrane. The hybrid membranes possessed excellent photocatalytic activities with and without H
2
O
2
. Moreover, the degradation of photocatalytic activities has been better controlled with the presence of H
2
O
2
.
The novel mesoporous silica hollow microspheres inside-loaded Ag nanoparticles (MSMAs) were fabricated through successively assembling Ag nanoparticles (AgNPs) and silica nanoparticles on the ...polystyrene beads and followed by the calcinations to remove the organics. The dosage of AgNO3, polyvinylpyrrolidone (PVP), tetraethoxysilane (TEOS) and ammonia was investigated to explore the variation in the morphology of the MSMAs such as the AgNP loading amount and the porosity of silica shell. Moreover, the Ag release property and long-term antibacterial activity of as-prepared MSMAs were also studied. The results show that the loading amount of AgNPs can be regulated by controlling the dosage of PVP or AgNO3, while the size of the pore in silica shell is increased with TEOS dosage. Lowering the PVP/AgNO3 mole ratio (>1.5) is favorable to obtain the MSMAs with high Ag loading density. High Ag loading amount as well as large pore size will increase the Ag+ ion release rate, leading to the more efficient diffusion of Ag+ ions from the interior of the silica hollow microsphere to the external medium through the pore channels in the shell. The long-term antibacterial activity is mainly determined by the Ag+ ion release rate, and the highest antibacterial activity can remain at a high level of up to 96% for long periods of six months.
•The mesoporous silica microspheres inside-loaded AgNPs are prepared controllably.•The loading behavior of AgNPs on the negative curvature surface is studied.•The assembly of silica colloids is studied from the perspective of adjusting porosity.•The Ag release can be controlled by regulating AgNP loading and porosity of silica.
•TiO2/Bi2WO6 microflowers are synthesized via hydrothermal method.•The absorption edge of TiO2/Bi2WO6 extends to a visible wavelength of 470 nm.•The heterojunction between TiO2 and Bi2WO6 effectively ...prolongs carrier lifetime.
Highly dispersed TiO2-modified Bi2WO6 microflowers were synthesized by using the hydrothermal method. The morphology and structure of as-prepared samples were characterized by SEM, TEM, EDS, XRD, Raman, UV-vis DRS, and TR-PL spectra. The heterostructured TiO2/Bi2WO6 exhibits a higher photocatalytic activity than pure TiO2 and Bi2WO6 under visible and UV-vis light irradiation. In addition, the recycling experiments indicate that TiO2/Bi2WO6 is excellent stability even after 5 five cycling runs. TR-PL spectra confirm that the coupling of Bi2WO6 with TiO2 significantly prolongs the lifetime of charge carriers. The enhanced photocatalytic activity of TiO2/Bi2WO6 is mainly attributed to the optimized bandgap and heterojunction, which absorb more visible light and prolong the carrier lifetime.
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•Bi2MoxW1-xO6 solid solutions with hollow microsphere structure were obtained for the first time.•Lattice parameters of Bi2MoxW1-xO6 were refined by Rietveld method.•High ...photocatalytic activity and good cycle stability have been achieved.•The formation mechanism of the hollow structure was the Kirkendall effect.
Semiconductor photocatalysis is an effective green way to combat water pollution. For the first time, this study reports a novel method to develop Bi2MoxW1-xO6 solid solution with microsphere structure through anion-exchange method. All Bi2MoxW1-xO6 samples exhibit an Aurivillius-type crystal structure without any secondary phase, confirming that in complete solid solutions as the value of x increases, the band gap energy of Bi2MoxW1-xO6 solid solutions decreases, while the optical absorption edge moves to longer wavelength. The Raman spectra research shows an increase in orthorhombic distortion with progressive replacement of W sites in Bi2WO6 with Mo6+ ions. Compared to Bi2MoO6 and Bi2WO6 samples, Bi2Mo0.4W0.6O6 sample displayed best photocatalytic activity and cycling stability for degradation of RhB dye. The enhanced photocatalytic activity of Bi2Mo0.4W0.6O6 sample can be synergetically linked to hierarchical hollow structure, enhanced light absorbance, and high carrier-separation efficiency. Additionally, the hollow Bi2MoxW1-xO6 microspheres formation can be attributed to the Kirkendall effect.
A novel porous magnetic composite CoFe2O4–SiO2 (CF–S) was prepared by a simple template method. After facile amino-functionalization, it exhibited bigger adsorption capacity and higher removal ...efficiency (>90%) for all the heavy metal ions (Cu(II), Mn(II), Cd(II), and Pb(II)) in single or mixed metal ions solution. The adsorption affinity for heavy metal ions was not much impacted by the presence of competitive ions. Moreover, effects of experimental parameters, including adsorbent dosage, solution pH, initial concentration, reaction temperature and time, were discussed. The isothermal adsorption results were well described by the Langmuir model, and the maximum adsorption capacities were 429.18 mg·g–1 (25 °C), 500.00 mg·g–1 (35 °C), 523.56 mg·g–1 (45 °C), and 555.51 mg·g–1 (55 °C) for Cu(II) ions. The adsorption kinetics fitted well with pseudo-second order kinetic model. Analysis of thermodynamic study for Cu(II) showed that the process of adsorption was spontaneous and endothermic in nature. The results indicated that the excellent adsorption was attributed to chemical adsorption through strong surface complexation, as well as the special structure of the CF–S–N composite.
In this work, a novel magnetic porous adsorbent was prepared
via
a sol-gel method for the removal of Ce(
iv
) from aqueous solution. The NiFe
2
O
4
/SiO
2
composite xerogels were characterized using ...SEM, BET, FT-IR, XPS, TEM, VSM and XRD. In addition, the effects of initial concentration, amounts of adsorbents, contact time, solution pH and temperature on the adsorption of Ce(
iv
) were investigated
via
batch adsorption studies. The results verify the formation of hierarchically porous structures with a specific surface area of 1085.3 m
2
g
−1
. The adsorption capacity for Ce(
iv
) at 25 °C is 114.56 mg g
−1
(91.65%), the adsorption of Ce(
iv
) onto the composite xerogels was better described by the pseudo-second-order kinetic model, and the data fit well with the Langmuir isotherm model. Thermodynamic parameters such as standard enthalpy (Δ
H
0
), standard entropy (Δ
S
0
) and standard free energy (Δ
G
0
) indicated that the adsorption of Ce(
iv
) onto composite xerogels was spontaneous and endothermic within the temperature range of 278-338 K. Moreover, the adsorbents showed good performance and recycling ability and could be separated by applying a magnetic field.
In this work, a novel magnetic porous adsorbent was prepared
via
a sol-gel method for the removal of Ce(
iv
) from aqueous solution.
Sol–gel process is a very unique wet chemical method for producing advanced materials in various areas of research. An increasingly evolution trend of this process is to combine with other ...technologies, such as surface modification, hybridization, templating induction, self-assembly, and phase separation, for preparing new materials possessing controllable shape, unique microstructure, superior properties, and special application. The review aims to present the synthesis of several typical sol–gel-derived materials (monodisperse nanoparticles, hybrid coatings, hollow microspheres, aerogels, and porous monoliths) via sol–gel process combining with other technologies . Some examples of application of the sol–gel-derived materials are also included.
The Ca
1−
x
Zr
1−
x
Ce
2
x
Ti
2
O
7+
δ
(0 ≤
x
≤ 0.4) series is synthesized via chemical routes, with microstructure/phase structure characterized by XPS, XRD, HRTEM, and SEM as well. The partial ...reduction of Ce
4+
in Ce
3+
in Ca
1−
x
Zr
1−
x
Ce
2
x
Ti
2
O
7+
δ
ceramics is observed from the Ce 3d XPS spectra. The XRD investigations and Rietveld refinements show that there are three crystal structures, namely monoclinic zirconolite-2M or zirconolite-4M, tetragonal perovskite, and cubic pyrochlore. The Ca and Zr sites of zirconolite structure are occupied by Ce
3+
and Ce
4+
ions, respectively. The zirconolite-2M → zirconolite-4M → pyrochlore transformation is based on the extent of Ce
3+
and Ce
4+
substitution. The zirconolite-4M phase tends to form at slightly higher substitution levels of Ce
3+
and Ce
4+
ions. At high substitution levels of Ce
3+
and Ce
4+
ions, cation rearrangement occurs resulting in the formation of pyrochlore structure. The chemical durability test is measured by the ASTM Product Consistency Test leaching method, and the normalized mass loss (
NL
Ce
) of Ce in the Ca
1−
x
Zr
1−
x
Ce
2
x
Ti
2
O
7+
δ
ceramics is shown in the order of 10
−6
–10
−7
g/m
2
.
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